As a technology applicable to a technology for switching a service to be provided to application software (hereinafter referred to simply as “application”), a technology is known which relates to change of setting information of a shared directory provided by a file server apparatus. According to the technology, a logical shared address designated to a client computer is converted into a physical shared address at which the shared directory actually exists.
As a technology applicable to a technology for switching a service to be provided to an application, also a technology is known which makes it possible to access a virtual resource obtained by a given procedure performed for an existing resource in the past. According to the technology, names of virtual resources, physical positions of actually existing resources, and names of procedures for handling the actually existing resources are retained and managed in an associated relationship with one another. This makes it possible to virtualize resources of a plurality of computer systems of a network information system to enhance the elasticity of the entire system.